Emergency pressure applicator



April 13, 1954 p, M, QLMAN 2,674,852

EMERGENCY PRESSURE APPLICATOR April 13, 1954 P. M. oLMAN 2,674,852

EMERGENCY PRESSURE APPLICATOR Filed sept. 5o, 1947 4 sheets-sheet 2 lll' illL r11/[Ill 1057-5@ Mms/,451 01AM/14 INVENTOR.

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APlvil 13, 1954 P. M. oLMAN EMERGENCY PRESSURE APPLIcAToR 4 Sheets-Sheet 3 Filed Sept. 30, 1947 ,4N-oever.

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.the brakes fail Patented Apr. 13, 1954 UNITED ls'm'rs ENT OFFICE Claims.

My invention relates generally to brake applying apparatus, and more particularly to apparatus of this type adapted to apply the brakes of a vehicle in the event of failure of the usual braking system. This application is a continuation-in-part of my prior application Serial No. 681,981, iiled July 8, 1946, for Brake Applying Apparatus, now abandoned.

While the hydraulically and pneumatically operated brakes of modern vehicles are designed to give trouble-free service over an extended period of time, there is always the possibility that the tubing which carries the brake fluid from the master or operating cylinder to the servomechanism in the wheel may, because of fatigue or other mechanical injury, develop leaks or completely fail, thereby rendering the brakes inoperable. There is sometimes a warning period during which the brakes do not work properly but are not totally inoperative; but occasionally without any advance indication whatsoever; In either event, it generally happens that the failure occurs when the brakes are most vitally needed, since under these circumstances the pressure supplied by the master cylinder is the greatest, and the hydraulic tubing fails completely under this greater stress. As a result, many serious accidents are caused each year by the failure of the brakes to operate at the time when they are most urgently required. While separate, hand-operated mechanical brakes are provided on most automobiles, these brakes are normally used for holding the car when it is parked, and are frequently worn to the point when they are no longer able to stop the car when it is in motion.

In the design of an emergency braking system, the system should be operative whether the hydraulic tubing or the master cylinder itself has failed, and should supply a substantially equal force to each of the wheels so that there is no tendency of the vehicle to swerve when the brakes are applied. Furthermore, separate systems should be provided for each wheel so that in the event of a serious mechanical failure wherein the servo-mechanism of one wheel is damaged, brakes on the remaining wheels may still be applied. It is also important that the braking force applied be such as to stop the vehicle in the shortest possible time, while still being insuiiicient to turn the vehicle over, should the brakes be applied while traveling at a high speed.

It is therefore a major object oi my invention to provide a brake applying apparatus which may be operated to apply the brakes of a vehicle when the normal system has failed.

Another object of my invention is to provide such an apparatus in which the force applied to each brake may be accurately controlled to balance .the brakes and to insure that the vehicle will not be overturned when the brakes are applied.

It is a further object of my invention to provide an apparatus of this type which may be used, with few modications, to operate hydraulic or pneumatically controlled brakes.

It is still another object of my invention to provide a device of this type which may be installed on existing vehicles with substantially no change in the braking system thereof, and with a vminimum amount of installation work required.

These and other objects of my invention will become apparent from the following description of a preferred and a modified form thereof, and from the drawings illustrating those forms, in which:

Fig. 1 is a vertical-sectional view of a rst form of my device, adapted to operate hydraulic brakes, showing the partsin their normal or unoperated position, with a schematic wiring diagram indicating the method of controlling the device;

Fig. 2 is a vertical-sectional View similarto Fig. 1 with the parts in the positions they occupy when the device is operated to apply the brakes;

Fig. 3 is a transverse cross-sectional view taken at 3--3 in Fig. 2;

Fig. 4 is a vertical-sectional view of a modified form of my device adapted to be used in brake systems which are operated by pneumatic means, and showing a slightly modied control;

Fig. 5 is a vertical-sectional view similar to Fig. 4, the parts being in the positions they occupy when the brakes have been actuated;

Fig. 6 is across-sectional view taken at 6 6 in Fig. 5;

Fig. 7 is a vertical-sectional view of a third form of my device adapted to be used in hydraulically controlled brake systems, showing the parts in their normal positions;

Fig. 18 is a vertical-sectional view similar to Fig. 7 showing the parts in their operated positions;

Fig. 9 is a cross-sectional View taken at 9 9 in Fig. 8, showing the catch arrangement adapted to hold the parts in their operated position;

Fig. 10 is a cross-sectional view taken at I ll--ID in Fie. 8;

Fig. 11 is a vertical cross-sectional view of a preferred form of my invention, adapted to be used in the operation of hydraulic brakes, and shown in its normal condition;

Fig. 12 is a view similar to Fig. 11 but showing the members in their actuated positions; and

Fig. 13 is a cross-sectional view taken at I3--I 3 in Fig. 1l and showing the face of the piston.

Referring now to the drawings and particularly to Fig. 1 thereof, the numeral IB indicates a generally T-shaped housing having fluid connections II and I2 at opposite ends of the cross-bar of the T, and having a cylindrical stem portion i3 whose end is closed by a plug Ill. My improved brake applying apparatus is designed to reduce the possibility of brake failure because of hydraulic line failure, and consequently, the housing I9 is adapted to be installed adjacent the wheel of the vehicle, with the fiuid connection i2 inserted in the corresponding connection therein, in place of the usual hydraulic line which is then attached to the fluid connection II. A cylinder I5, Slidably mounted within the stern I3, is normally held out of a passageway H formed between the iiuid connections I I and l2, but may be moved toward the cross-har of the T to close the passageway. When this is done, the parts are in the position shown in Fig. 2, and all fluid within the servo-mechanism is trapped therein, while fluid within the hydraulic line connected to the Jduid connection II has no eect upon the action of the mechanism. Fluid within the cylinder I5 may then be forced out through the fluid connection I2, and the brakes will be applied thereby.

As seen in Fig. 1, the stem I3 is made sufficiently long to receive plug It and the entire length of cylinder l5, with a space H left between them. .a solenoid is mounted on the stem portion I3 aligned with the space Il, and a plunger 2| extends through the wall of the stem portion and into the space, being moved further inwardly by the solenoid when the latter is energized. `Near its inner end, the plunger 2l is provided with a latch member 22 which is adapted to engage a cooperating latch member 23 attached to the upper end of the cylinder I5. A spring (not shown) is provided within the solenoid 2B to retain the plunger 2l in a normally retracted position, but its normal urging may be overcome by the energization of the solenoid to extend the plunger further into the space Il, thereby disengaging the latch members 22 and 23, and permitting the cylinder I5 to be moved downwardly into the passageway I6. To prevent the cylinder I5 from being moved upwardly into the space IT beyond its normal position, a stop or retaining ring 24 is mounted in an internal circumferential groove 25 in the stem i3 to hold the cylinder against upward movement which might disengage the latching members 22 and 23. Y

.Within the space I1, I mount a container 26 having a compressed gas therein, and a spring 21 bears against the container, or the plug I4 which holds it, and against the upper end of the cylinder l5 to urge the later downwardly. This downward movement, however, is normally resisted by the latch members 22 and 23; but when the solenoid 2D is energized, the latch members are separated and the cylinder is moved downwardly to the position shown in Fig. 2. To release the gas within container 26, the plunger 2I is provided with a point 30 at its innermost end which is adapted to bear against the container 2E and puncture the latter when the solenoid is energized. The compressed gas contained within the container 26 is thus released, at the same time that the cylinder I5 is released by the latching member 22 and is moved downwardly by the spring 21.

Within the cylinder I5 is an axial cavity 3l which is open at its upper end to the space I'I, and is closed at its lower end by a horizontal partition 32 and passageways 33 are formed in the lower portion of the wall of the cylinder to connect the cavity with the fluid coupling I2 when the cylinder is in its lowered position. The lower surface of the partition 32 is provided with a recess Bfi which is adapted to engage a corresponding boss 35 on the lower surface of passageway I6 to prevent any transverse movement of the cylinder I5 when the latter is in its lowered position.

Slidably mounted within the cavity 3i is a piston 36 which is normally held at the upper end of cylinder I5 but which may be moved downwardly to force any fluid within the cavity out through passageways 33. The piston 35- is preferably formed with a circumferential groove 3'! in which a sealing ring 38 is mounted so that none of the fiuid may pass around the piston instead of being discharged through passageways 33. It is to be noted that in this form of my device,

spring 2l bears against the upper edge of cylinder I5 and not against the upper surface of piston 36.

When the container 26 is punctured, the cornpressed gas container therein will act on the upper surface of the piston 36 and urge it downwardly. However, until such time as the cylinder I5 has been seated against the lower surface of passageway IE, it is undesirable to have the fluid within the chamber 3| forced outwardly through the passageways 33. To retain the piston 3E in its upper position until this has occurred, I provide a locking means somewhat similar to the pin and tumbler arrangement used in certain locks. As shown in Fig. l, this locking means includes a hole 43 formed in the piston 36, having a spring 4l therein which' is adapted to urge a pin s2 outwardly. A hole 43 is formed in the cylinder I5 to align with the hole d when the piston 36 is in its uppermost position; and a pin M, substantially the same diameter as pin 32, is mounted in hole 43 and extends outwardly from the cylinder, to fit into a longitudinally extending slot I formed in the inside surface of the stem portion I3. With the various parts of the brake actuator in their normal position, as shown in Fig. 1, spring M urges pin 42 outwardly to fit into the hole 43 and thereby prevent downward movement of the piston 35 with respect to the cylinder I5. When the cylinder is moved downwardly, however, as shown in Fig. 2, the pin 44 reaches the end of slot 45 and is forced inwardly, thereby moving the pin 42 inwardly until it is fiush with the surface of the piston 3S. At that instant, the piston 36 is released from cylinder I 5 and the pressure of the gas which has been released from container 26 urges the piston downwardly, thus forcing any iiuid contained within the cavity SI out through the passageways 33. AS shown in the drawings, prefer to use a pair of pin locks located diametrically opposite each other to prevent the piston 3s from being tipped at an angle and thus jamming within the cylinder I5.

To complete the device, I provide a pair of sealing members to prevent the escape of pressure from the space Il', around the cylinder I5, and to the fiuid connection I l. At the lower end of the stein I8, I form a circumferential groove 45 adapted to receive a sealing ring el which bears against the cylinder I5; and the upper end ofthe cylinder is provided with a circumferential groove 48 which carries a sealing ring i9 bearing against the inner surface of the stem I3. In this way, the cylinder l may be made to slide freely within the stem I3 while a uidtight seal is maintained between the space I1 and the fluid Yconnections I I and I2 at all times.

To operate the solenoid 25, a pair of conductors 50 and 5I are connected through a switch 52, preferably of the double pole, single throw variety, to a source of electrical energy 53. The source 53 may be customary storage battery found in most vehicles, or may be `a generator or any other suitable source of power. The switch A52 may be mounted on the steering column of the ves hicle, on the instrument panel, or at any other suitable place. It 'should be readily accessible, however, so that in the event of an emergency, it Vmay be operated instantly to close the circuit to the solenoid 2D.

Since the cylinder I5 must have its cavity 5I iilled with iluid in ordm' for the device to op-v crate, I provide a ll'er hole 55 in the piston 36 which is closed by a threaded plug 56 except when the cavity is being filled with fluid, or air is being removed therefrom. Similarly, I provide a removable plug 5l in the fluid connection I2 to permit the brakes of the vehicle to be released without the necessity of removing the entire housing I0.

Operation of Figs. 1 to 3 When my improved emergency brake applicatorvhas been installed on a vehicle, it will no1'- mally be installed so that the fluid connection I2 is tted into the coupling member mounted on the axle of the vehicle, and the fluid connection I I will have the usual hydraulic line from the master cylinder of the braking system connnected to it. The cavity 3| is filled with 'a suitable hydraulic iluid; the piston 3e is held in its uppermost position by the pins 42 and 43 and cylinder I5 is raised to bear against the retaining ring 25 and is held there by the latch members 22 and 23l Container 26 is lled with a compressed gasl preferably carbon dioxide or some other inert gas, and spring 2l is compressed to urge the cyl inder I5 downwardly. Passageway I e thus provides an unrestricted iluid connnection between couplings I I and I 2, and the brakes of the vehicle may be operated in their normal manner and with the usual results until some emergency arises, at which time switch 52 is closed.

When switch 52 is closed, solenoid 2Q is energized and plunger 2| thereof is moved inwardly to release latchingmembers 22 and 23 and to puncture container 25. As soon as latching mem# ber 23 is released, `cylinder I5 is moved downwardly by the action of spring 2l, while the puncturing of the container 26 releases the gas contained therein so that thevpressure in space I'I isigreatly increased` When cylinder I5 reaches the lo'wer limit of its travel and fbottoms against the lower surface of passageway I5, pins III are moved inwardly by reason of their reaching the lower ends of slots 45. 'IljieV inward movement of pins 44 causes the pinsv42 to be moved inwardly against the urging of spring el, andfwhen the abutting surfaces of pins Afiand 5.4 are aligned vwith the inner surface of cylinder' I5, piston 3e is released from its uppermost position,V and is moved downwardly to the lower end of thecylinder by the pressure in space I'I. The brake fluid contained within vthe cavity 3| is thereby forced outwardly through the passageways 3 3 and throughthe fluid coupling I2 to the servo-mecha gvnisrn of the brakes to operate the lattenthe quanthe piston I tity of fluid within the cavity being suiiicient to charge the servo-mechanism, while the pressure in space Il is sufficient to supply the continuing pressure necessary for the operation of the brakes. By properly correlating the amount of compressed gas within container 25, with the volume of space II and the volume of cavity 3|, the braking force exerted on the wheels may be adjusted to lock the wheels at a predetermined speed, but this same force will be insuicient to lock the wheels at any greater speed. In this way, the braking force applied to the wheels of a vehicle traveling at a relatively high speed will be suflicient to slow the vehicle very rapidly, but will be insulcient to turn the vehicle over. When the speed of the vehicle has been reduced to the value at which the wheels will lock, the principal danger of overturning the vehicle has been eliminated and the brakes will then lock and complete the task of stopping the vehicle. The brakes will remain in this locked condition until the pressure in the servo-mechanism is released either by removing the' plug 5'I from the coupling I2; or by removing the plug III and permitting the gas in the space Il to escape.

Description of Figs. 4 to 6 In Figs. 4 to 6, I have shown a modiiicationof my device which may be used to operate pneumatically controlled brakes of vehicles when the normal operating force consists of a positive pressure instead of a suction or partial vacuum. In the drawing, parts corresponding to similar members in Figs. 1 to 3 are indicated by corresponding numbers 100 units larger. Thus a body member III) has a master cylinder hydraulic connection III and a servo-mechanism hydraulic connection I I2 joined by a iluid passageway I IS from which a perpendicular stem portion I I3 extends, while a release plug |51 permits the release of the brakes after they have been applied. A piston ||5 similar to piston I5, is slidably mounted in the stem portion II3; and a solenoid |25 has a plunger I2| which extends into a space I I'I above I5, and carries a latchhig member |22 which engages with a second latching member I 23 attached to the upper portion of the cylinder. A stop, such as a retaining ring mounted in a groove |25, limits the upward travel or" the cyl inder H5, while a plug H4 is tted in the upper end of stenrportion IIS so that a spring I2? may bear against it and the upper surface oi the cylinder to urge the latter downwardly.

The lower end of the stem I I3 is provided with a circumferential groove |55 which receives a sealing ring '|47 bearing against the piston I 5; and the upper end of the latter is provided with a similar groove |48 adapted to receive'a sealing ring |49 which bears against the interior surface of the stem IIS.` The lower end of the cylinder I I5 i's closed by a partition' I 52, while passageway |33 is formed in the side of the pistonl adjacent the fluid connection I I 2. The `lower surface lofthe passageway I I 6 is provided with a boss i115 adapted to fit into a recess I in partition |32; and a pointed projection YIiiIl is centrally located ron the boss to extend through a hole IIE in the 'partition' |32 when the cylinder is in its lowest position. Conductors |55 and I5! connect the solenoid' |20 through switch |52 to battery |53; and all the parts sofarrnenticned, with the' exception of projection and hole ISI, are similar to the similarly numbered partsofthe form shown in Figs. 1 to 3.

. At the upper end of` cylinder H5, I' provide a receiving member |62 which is held to the top of the cylinder by screws |83 or other suitable means, and which extends downwardly into the interior of the cylinder and receives a container |64 holding a compressed gas. The container ld may be of the type used to carbonate water and other beverages in siphon bottles, and generally provided with an easily punctured closure formed in the neck of the container. The receiving inemn ber |62 is adapted to receive the container ld with the neck pointing downwardly where it may be contacted by the projection |66; and a cap |65 is screwed to the upper portion of the receiving member to hold the container therein against longitudinal movement. It will thus be seen that when the cylinder is moved downwardly, as shown in Fig. 5, the projection |56 will extend through the hole |6| and puncture the seal in the neck of the container |64, while holes |55 or grooves permit the compressed gas to escape from l the container |64 to ll the cavity i3! in the cylinder H5.

Any pressure within the cavity |3| will act upon the upper wall thereof and on the boss 235 to tend to raise the cylinder H5 and permit the increased pressure therein to escape through the hole |6|. 'Io prevent this, I provide a catch means which is adapted to hold the piston i5 in its lowermost position until intentionally and manually released. While other forms of catches may be used, I prefer to use a pin |19 which is mounted in a radially drilled hole |1| in the piston H5, and which is urged outwardly at all times by a spring |12 which bears against the inner end of the hole and against the pin. Near the lower end of stem |3, I provide a hole |13 the same diameter as hole |1| and adapted to be aligned with the latter when the cylinder H5 is in its lowermost position. A boss |14 surrounds the hole |13 on the outside of the stern |13, and a plug |15 is screwed into hole |13 so that the latter is normally covered but may be opened. A longitudinal groove |16 extends upwardly from hole |13 in the wall of the stem i3 to receive the pin and act as an aligning means to prevent the rotation of the cylinder l5. When the cylin- L der has been released and moved to its lowermost position by spring |21, pin |10 is moved ou*- wardly by spring |12, entering the hole |13 and locking the cylinder against upward movement until the plug |15 is removed and the pin forced inwardly.

Operation of Figs. 4 to 6' The various parts of the device are normally in y the position shown in Fig. 4, with the seal in the neck of the container |64 unbroken. However, when it is desired to operate the pneumatic brake of a vehicle by means of my improved emergency brake applicator, switch |52 is closed, completing the circuit from battery |53 to solenoid |20. When solenoid |20 is energized, plunger |`2| is moved inwardly, thereby disengaging the latching members |22 and |23 and permitting the cylinder ||5 to be moved downwardly under the urging of spring |21. As cylinder i5 reaches the downward limit of its travel, projection i6@ passes through hole |6| to bear against and finally puncture the seal in the neck of container Nid, permitting the compressed gas therein to escape into cavity |3| and then outwardly through pas'- sageway |33. At the same time this is occurring, pin |18 is being aligned with hole |13, whereupon the pin is moved outwardly by spring V|12 to the position shown in Fig. 5, where it locks the cylinyder |15 against upward movement. The compressed gas originally within the container |64 is thus conducted through uid connection ||2 to the servo-mechanism of the brakes, operating the iatter and bringing the vehicle to a stop.

By properly correlating the amount and pressure of the gas within container |64, with the volume and pressure requirements of the servomechanism of the brakes, the braking force exerted by the latter may be adjusted so that the vehicle will not be overturned if traveling at a very high speed, but instead will be slowed until such time as it is safe for the wheels to be locked. The operation of this form of my device is thus seen to be quite similar to that of my preferred form with the exception that a compressed gas instead of a liquid under pressure is used to operate the servo-mechanism of the brakes. As in the form shown in Figs. l to 3, when the brakes of a vehicle have been operated by means of this emergency brake applying device, they will remain in operated condition until the pressure is released by removing the plug |51 from the iluid coupling ||2, or :by removing plugs ||4 and |15 and releasing pin |16 from hole |13.

Description of Figs. 7 to 10 In both of the previously described forms, a compressed gas, normally held in a sealed container, is released by puncturing that container to operate the brakes of a vehicle. As a result, when the brakes have once been operated by these devices, it is necessary to replace the container holding the compressed gas in addition to returning the piston to its normal position. Where it is anticipated that the need or desirability of replacing the container after each operation will be very slight, the form of device shown in Figs. '1 to l0 may be used to operate hydraulic brakes. It will be seen that many of the parts of the device shown in Figs. '7 to 10 are similar to those in the device shown in Figs. l to 3, and similar parts of the optional form have been given reference numerals in the two hundred series to correspond to similar parts of the first form.

Thus, this optional form of my device includes a T-shaped housing 2|0, corresponding to the housing I0 of the preferred form, having uid couplings 2| and 2|2 at the ends of the cross-bar of the T and having a stem portion 2|3 closed by a plug 2 l. Slidably mounted in the stem 2|3 is a cylinder 2|5 which is normally held in an upper position, shown in Fig. 7, but which may be lowered to close a fluid passageway 2 6 extending between fluid couplings 2|| and 2|2. A space or cavity 2|1 is formed between the upper surface of the cylinder 2|5 and the @plug 2|4; and a solenoid 2243 is attached to the stem 2|3 so that its plunger 22| extends into the space where it carries a latching member 222 adapted to engage a latching member 223 attached to the upper surface of the piston 2 i 5. To limit the upward travel of the cylinder 2|5, a stop such as a ring 224 is mounted in a groove 225 formed in the interior surface of the stem 2|3. The cylinder 2|3 is formed with a coaxial central cavity 23| which receives a piston 236; and a spring 221 extends between the cap 2M and the piston to urge the latter downwardly.

The lower end of cylinder 2|5 is closed by a partition 232 having a rrecess 234 therein adapted to engage a boss 235 formed in the'lower surface of the passageway 2 I5 when the cylinder is in its lowermost position. Passageways 233 are formed in the lower end of cylinder 2 I5 on the side nearest the fluid coupling 212, and as in the other form, fluid within the cavity 1231 may be forced outwardly through the passageways 233 when the piston 236 is moved downwardly. A groove 24B is formed in the stem portion 213 at the lower end thereof to receive a sealing ring 241 which bears against the cylinder 215 to prevent the passage of fluid between the piston and the stem portion. A similar sealing means, including a groove 228 containing a sealing ring 243 is formed in the upper portion of cylinder 255 so that both the upper and lower ends of the cylinder are sealed at all times. Similarly, a groove 231 is formed in piston 236 to receive a sealing ring 238 which bears against the inner surface of cylinder 215 to prevent the passage of fluid from cavity 231 into space 211. A filler hole 255, closed by a threaded plug 253, permits the filling of cavi-ty 231 with iiuid and the bleeding of air therefrom; and a release plug 2 51 provided in fluid connection 2 l 2 to permit the release of pressure from the servo system after the vehicle has been stopped.

The normal position of piston 233 is at the upper end of cylinder 2id, and it is held in this position by a pin 242 slidably mounted in a hole 2st and urged outwardly by a spring 241 which bears against the inner end of the hole and the inner end of the pin. A hole 233 is formed' in the cylinder 215 to align with hole 243? when the piston 233 is in its uppermost position, and a pin 22d is inserted in hole 243 to bear against the outer end of pin 242 and extend outwardly from the cylinder when pin 242 extends into hole 243. To receive the outer end of 4pin 244, a longitudinally extending groove 245 is formed in the inner surface of stem 213,` terminating at a point just above the position of the pin 244 when the cylinder 255 is in its lowermost position. Two of the pin and groove catches are provided for the piston 233, and as previously mentioned, they operate to hold the piston in its uppermost position until such time as the cylinder 215 hasV been moved downwardly toits lowerrnost position', at which time the pins 243 are forced inwardly' to align the outer ends of pins 2412 with the piston 23d, whereupon the latter is released and may be moved downwardly. Connectorsv 25E)- and 251 connect the solenoid through a suitable switch to a source of power in a manner similarto that described in connection with the previously described forms of my device.

To hold the cylinder 215 in its'lower'most position when it has been moved there by springs 221, a catch, similar to that shown in Figs'. 4 and 5 is provided. As shown best in Fig. 9, cylinder' 215 is provided with an outwardly extending radial hole 21E adapted to receive a` pin 211`and a spring 22. A similar' hole 213, aligned with hole 21|' when the cylinder 215 is in its lowerinost4 position, is formed in stern 213`which is provided with a boss 214;l surrounding the hole 213 at its outer end. A plug 215 is screwedinto hole 213: anda spring operated catch similar to that shown in connection with my pneumaticv control form' is thus provided. However, since grooves 2451eceive pins 25,4 and' prevent the rotation of cylinder 215 about itstaXis, no groove is requiredfor pin 21e and the latter may ride upon the" inner surface of stem 213.

Operation ofV Figs. 7 to 10 WhenVV the solenoid 22 3 of i this optional i formi of ton 236 is held to cylinder 215 by the pins 242, and the downward urging of spring 221 is thus transmitted to the cylinder which is now free to move downwardly. When the cylinder 215 has reached its lowermost position, as shown in Fig. the fluid connection previously existing between fluid couplings 21 i and 212 has been closed and cavity 23i is now open, through passageways 233, to the servo-mechanism of the bralres which connected to uid coupling 212. When the piston 215 reaches its lowermost position, pin 21o is moved into hole 213 of the stem member 253 by spring 222, thereby holding the cylinder in its lowered position and preventing any pressure within the fluid coupling 212 from raising the cylinder and reopening the fluid passageway 21'3. At the same time that pin 2111 snaps into hole 213, the downward movement of the cylinder has brought pins 244 to the end of grooves 24e, where the former are forced inwardly to align the outer ends or' pins 242 with the inner surface of the cylinder so that that piston 233 is then released from its normal position.

The entire force of spring 221 is then directed solely against piston 231i, and the latter is therefore moved downwardly, forcing any hydraulic iiuid within chamber 231 outwardly through passageways 233 to operate the servo-mechanism of the brakes connected to fluid coupling 212. The brakes of the vehicle are thus operated; and the force exerted by spring 221l is correlated with the servo-mechanism so that the braking force exertedby the wheels of the vehicle is insufficient to overturn the latter should 1t be traveling at a relatvel'y high speed when the brakes are applied. At some lower speed, this force may be sufficient to lock the wheels of the Vehicle, but this speed is sufliciently low so that there is no danger of overturning thevehicle.

Once the brakes have been applied by means of this device, they will remain energized until the pressure within the servo-mechanism is reduced by removing plug 251 from the fluid coupling 2 1'2, or by raising cylinder 215 or piston 236. To return the cylinder 215 and piston 23e to their normal positions, plug 2&4 is removed to relieve the pressure exerted by spring 221, and plug 215 is removed to permit pin 21d to be forced inwardlyso that it no longer holds the cylinder in its lowermost position. The latter may then be raised to itsV normal position and latch mem- 'bersv 222 and 223k engaged to hold it in that position; and piston 236 may be'rased to its normal position, whereupon pins 2132 will be urged outwardly `to enter holes 243 where they will hold the piston against downwardmovement. Spring 221 is' then compressed and plug 2id reinstalled, and if the cavity 231 is nlled with hydraulic fluid, the device is again ready for operation. if the chamber 231' is made sufficiently large, and if the spring 221 exerts a suflicient force on the piston 236, this device may be used to operate the brakes of a vehicle havinga pneumatically oontrolled system, though generally better results will be obtained by using the form of device shown in Figs. 4 to 6- in such application.

Description of Figs. 11 to 13 n Thepreferred form' of my apparatus is shown inFigs: 1v1 to` 13 and includes generally the same broad features of construction and arrangement of" partsf as those' of the forms previously' described, withl certainlim'provements and modification'siwhi'ch simplifyVV the manufactur'eand better ther operaionbf the device.

As'show'nf in theseylews, thepreferred form of my device includes a generally cylindrical housing 313 having a fluid connector 312 at one end thereof, adapted to be connected to the servomechanism of the brakes (not shown). On the side of the housing 310 and near the middle thereof I provide another duid connector 311, similar to the fluid connector 312, and adapted to be connected in any suitable manner to the master cylinder (not shown) of the braking system. The interior of the housing 310 is hollowed to form a central chamber 311, and a fluid connection is thus established from the connector 311, through the chamber 311, to the connector 312.

The end of the housing 310 in which the ccnnector 312 is mounted is closed by a wall 314, while the opposite end of the housing is closed by a threaded plug 315, which is tightly and rmly held therein. As previously indicated, the housn ing 313 is provided with a chamber 31'1, and it will be noted that the diameter of the chamber is larger at the end nearer the plug 315, and smaller at the end adjacent the wall 314. Between the two sections of dilerent diameter, I provide a tapering or conical shoulder section 316 which is located between the wall 314 and the connection 311, immediately adjacent the latter.

Slidably mounted in the central chamber 31'1 is a piston 32) normally adapted to remain adjacent the plug 315 but capable of being moved away from the latter toward the Wall 314. To insure the proper operation of the device, I form the piston 32B so that it ts snugly Within both the larger and smaller diameter sections of the chamber 31'1, and consequently the piston is stepped to provide a section 321 of smaller diameter and a section 322 of larger diameter, these two sections being joined by a tapered portion 323 shaped complementally to the shoulder 313. When the piston 3211 is in its normal position, a compartment is thus formed between the smaller face of the piston and the wall 314, and an annular space or cavity is formed between the smaller section 321 and the inner wall of the housing 311), extending from the shoulder 313 to the tapered section 323. It is to this annular space that the connector 311 is directly fluid connected.

To establish a fluid connection between the end compartment of the chamber 311 and the annular space or cavity just mentioned the end of the section 321 is provided with one or more slots 324 which extend inwardly through the body of the section to a point adjacent the shoulder 316. In this way, fluid may flow from the annular space into the larger compartment as indicated by the arrows in Fig. 11, thereby providing a iiuid connection between the connectors 31 1 and 312.

Between the end of the groove 324 and the tapered portion 323, I provide an annular groove 325 adapted to receive a sealing member 326, such as a so-called O-ring. The outer diameter of the sealing member 326 is such that it is spaced from the shoulder 316 in its normal position, but is adapted to make a sealing t with the walls of the housing 310 when the piston 3211 is moved toward the wall 314. A similar sealing means is provided in the piston 3211 near its opposite or larger end, this means including a groove 3311 adapted to receive a sealing member 331 such as an O-ring similar to that previously described.

To complete the preferred form of my device, I locate a small explosive charge within the plug 315 so that the charge may be detonated and thereby force the piston 3213 toward the wall 314. One method of accomplishing this is to provide the plug 315 with an axially extending threaded hole 332 into which a correspondingly threaded plug or cap 333 may be placed. The inner end of the plug or cap 333 is hollowed to receive an explosive charge 334, such as a small amount of black powder, the charge preferably being held in place by a thin moisture-proof membrane 335. Embedded within the explosive charge 334 is a detonator (not shown) adapted to be operated by an electric current, and wires 331i and 351 lead from the detonator to a suitable electrical controlling means such as that previously described in connection with the other forms of my invention and illustrated in Figs. 1 and 4.

Operation of Figs. 11 to 13 Under normal conditions, the various elements of my preferred form of emergency brake applying apparatus will be disposed within the housing 3111 in the positions indicated in Fig. 11. When such is the case, fluid from the master cylinder of the braking system williiow through the connector 311 into the annular space surrounding the smaller section 321 of the piston 320. From this annular space, fluid will pass through the grooves 324 into the larger compartment between the end of the smaller section 321 and the wall 314, leaving the compartment through the connector 312 and going to the servo-mechanism of the brake. Any tendency of acceleration or vibration to move the piston 323 away from the plug 315 and toward the wall 314 is overcome by the fluid within the compartment 314 and the end of the piston 326, the fluid therein acting substantially as a, non-elastic mass. Furthermore, any pressure which may be applied through the connector 311 increases the pressure within the annular space surrounding the smaller section 321, this force being transmitted to the tapered section 323 to urge the latter and the piston 320 toward the plug 315.

When the pressure from the master cylinder is released, the pressure within the servo-mechanism reverses the flow of fluid so that it is now from the connector 312, through the slots 324,

` and out through the connector 31 I. It will be apparent that this action likewise tends to force the piston 320 toward the plug 315. Consequently, under normal circumstances the brakes of the vehicle equipped with my improved apparatus operate in the usual manner with no substantial restriction interposed between the master cylinder and the servomechanism of the brakes.

However, when an emergency arises and the normal operation of the master cylinder is not effective to stop the vehicle, a switch such as the switch 152 previously described is closed to complete an electrical circuit to the conductors 350 and 351, thereby exploding the charge 334 and rupturing the membrane 335. When this occurs, the piston 3211 is driven away from the plug 315 toward the wall 3l4 with considerable force, the motion of the piston being stopped by the tapered section 323 hitting and bearing against the shoulder 31'6. At this time, the various members of my device are in the position indicated in Fig. l2.

It will be realized that the movement of the piston 320 to the position indicated in Fig. 12 has acted to prevent the escape of fluid through the slots 324 by moving the latter away from the annular space or cavity adjacent the connector 31 I.

Shortly thereafter, the sealing member 323 has contacted the inner walls of the housing 310 to form a fluid-tight seal, and further movement of the piston 321] hasforced al1 or substantially all 13 of the fluid in the compartment between'the wall 3 I 4 and the end of the piston 320 through the connector 3|2. As a result, the fluid connector 3|I has been electively disconnected from the servomechanism of the brakes, and the hydraulic iluid within the housing 3| 0 has been forced into that mechanism, thereby setting the brakes-and bringing the vehicle to an immediate stop. The gas created by the explosion of the charge 334 remains within the housing to maintain the pressure of the hydraulic fluid within the servo-mechanism and the brakes may be released only by loosening` or removing the plug or cap 333 so that these gases may escape. When this is done, the pressure of the uid within the servo-mechanism will move the piston 320 toward the plug 3 |`5 until it reaches its original position shown in Fig. 11. Consequently, no air will be admitted to the hydraulic system by reason of the operation of my device,

and maintenance costs and procedures will thus be reduced to a minimum. Disregarding any repairs or maintenance work on the braking system itself, after the operation of my device it is only necessary to replace the plugs or caps 333 in order to return the complete braking system to its original condition. The plugs or caps 333, being Very simple to manufacture and formed of relatively inexpensive materials, may be replaced at a very nominal cost so that the benefits to be gained from the use of my device are tremendous.

With a few simple changes, it is possible to modify my preferred form of device to operate pneumatically controlled brakes of the positive pressure type. To accomplish this, the piston 326 may be hollowed and provided with a container holding a compressed gas, such as the container |64 shown in Figs. 4 and 5. The adjacent wall 3|4 will then be provided with a projection adapted to puncture the seal of the container |64 `and permit the gas contained therein to escape, similar to the form shown in Figs. 4 and v5 and previously described.

To insure that the piston 320 will remain adjacent the end wall 3 I4 when the device is used in the pneumatic system, the charge 334 may be proportioned .so that after it is exploded, the pressure between the plug 3|5 and the larger end of the piston 32|] is greater than the pressure between .the wall 3|4 and the smaller end of the piston. As an alternative means, .a sliding pin type of detent may be used, such as the pin sliding within the groove |13 of the form shown in Figs. 4 and 5.

By changing the solenoid 2.0, |20, or 220 of the forms shown in Figs. 1 -to 10 so that the plunger 2|, |2l, or 22| is moved .inwardly to release the latching member when the solenoid is de-energized instead of when thesolenoid is energized, the device may be used .to set the brakes -of towed vehicles, such as trailers, should the latter break loose from the vehicle which is pulling them. Should such a system be used, the operating switch would then, .of course, be a normally closed switch which would maintain the solenoid energized at all times until the circuit is broken, either by the switch or by the separation of the wires in the circuit. While a slight `modiiication would be necessary to .adapt the preferred form Vof my device, shown in Figs. 1l to 13, to this type of operation, it is believed these changes will be apparent to those skilled in the art.

While I have shown and described preferred and optional forms of my device, it is apparent that modifications may be made therein which do not depart from the scope of the invention; and I do not wish to be limited to the particular form or arrangement of parts herein described and shown, except as covered by my claims.

I claim:

1. An emergency brake applicator which includes: a housing having a chamber therein, said chamber having a portion of larger diameter at one end and a portion of smaller diameter at the other, said portions of larger and smaller diameter being substantially cylindrical and joined by a tapered portion which is short compared `to said cylindrical portions; a piston slidably mounted in said chamber, having a smaller section adapted to fit within said smaller portion of said chamber, a larger section adapted to t within said larger portion of said chamber, and a tapered section joining said larger and smaller sections shaped complementally to said tapered portion of said chamber, said piston normally being retained near the larger y'end of said chamber to form a compartment bounded by the walls and smaller end of said chamber and the end of said smaller section of said piston, and forming an annular space between the walls of said chamber forming said tapered p0rtion and said larger portion, and the smaller section and tapered section of said piston; arst iluid connector attached to said housing, adapted to be connected to a fluid controller, and makiluid connection to said annular space; Va second fluid connector attached to said housing, adapted to be connected to a iluid operating means, and making iiuid connection to the end of said compartment remote from said piston, said piston having passageways formed in the end of the smaller section thereof to provide'a fluid connection between `said compartment and said annular space when 4said piston is in its normal position; andelectrically detonated explosive means mounted in said housing at the larger end of said chamber, operable to drive said piston toward said second connector, whereby said fluid connection between said compartment and said annular space is first closed, and fluid within said compartment is then compressed land discharged through said second connector.

2. An emergency pressure applicator which includes: a housing having a chamber therein, said chamber having a portion of larger diameter at one end and a portion of smaller -diameter a-t the other, said portions of larger and smaller diameter being substantially cylindrical and joined by a tapered portion therebetween; a piston slidably mounted in said chamber, having a smaller section adapted to 'fit within said smaller portion of said chamber, a larger seotion adapted to nt within said larger portion of said chamber, and a tapered section joining said larger and smaller sections shaped complementarily to said tapered portion of said chamber, said piston being normally -retainedvnear the larger end of said 'chamber to form a compartment bounded by the walls land smaller end of said chamber and the end of said smaller vsection of said piston, and forming an annular space between the walls of said chamber forming said tapered portion and said larger portion, and the smaller section and tapered section of said piston; a iirst fluid connector attached to said housing, adapted to be connected to a fluid controller, and making iluid connection to said annular space; a second fluid connector attached to said housing, adapted to be connected to a fluid-operating means, and make duid connection to the end of said compartment remote from said piston, said piston having a passageway formed in the end of said smaller section thereof to provide a iluid connection between said compartment and said annular space wlhen said piston is in its normal position; and means connected to said housing at the larger end of said chamber, and operable to drive said piston toward said second connector, whereby said fluid connection between said compartment and said annular space is first closed, and fluid within said compartment is then compressed and discharged through said second connector.

3. An emergency pressure applicator which includes: a housing having a chamber therein, said chamber having a portion of larger diameter at one end and a portion of smaller diameter being substantially cylindrical and joined by a tapered portion therebetween; a piston slidably mounted in said chamber, having a smaller section adapted to t within said smaller portion of said chamber, a larger section adapted to fit within said larger portion of said chamber, and a tapered section joining said larger and smaller sections shaped complementarily to said tapered portion .of said chamber, said piston being normally retained near the larger end of said chamber to form a compartment bounded by the walls and smaller end of said chamber and the end of said smaller section of said piston, and forming an annular space between the walls of said chamber forming said tapered portion and said larger portion, and the smaller section and tapered section of Said piston; a. first fluid connector attached to said housing, adapted to be connected to a fluid controller, and making iiuid connection to said annular space; a second fluid connector attached to said housing, adapted to be connected to a duid-operating means, and make uid connection to the end of said compartment remote from said piston, said piston having a passageway formed in the end of said smaller section thereof to provide a fluid connection between said compartment and said annular space when said piston is in its normal position, and said piston having an annular groove in said smaller section inward of said passageway; an O-ring in said annular groove in said smaller section, said O-ring being capable of making a sealing t with the wall of said smaller chamber portion when said piston is moved from its normal position toward said second connector; and means connected to said housing at the larger end of said chamber, and operable to drive said piston toward said second connector, where- -by said iiuid connection between said compartment and said annular space is first closed, and fluid within said compartment is then compressed and discharged through said second connector.

4. A device of the class described which includes: a housing having a generally cylindrical chamber therein, said chamber having a large bore and a small bore with the axes of said bores being parallel, said housing having an intake port opening into said large bore and an outlet port .opening into said small bore; tapered shoulder means positioned in said housing to provide a gradual transition from said large bore to said small bore; a piston slidably mounted within said chamber, having a large section of size corresponding to said large bore and a small section of size corresponding to said small bore, said piston being slidable from a iirst position where said small section is substantially withdrawn from said small bore to provide a duid connection between said intake and outlet ports, to a second position where said small section is substantially wholly within said small bore, said piston having an annular groove in its small section; and an O-ring in said annular groove in said piston, said O-ring being capable of making a sealing fit within the wall of said small bore when said piston is in said second position, thereby interrupting the fluid connection between said intake and outlet ports through said chamber.

5. A device of the class described which includes: a housing having a generally cylindrical chamber therein, said chamber having a large bore and a small bore with the axes of said bores being parallel, said housing having an intake port opening into said large bore, and an outlet port opening into said small bore; a tapered shoulder means positioned in said housing to provide a gradual transition from said large bore to said small bore; a piston slidably mounted within said chamber, having a large section of size corresponding to said large bore and a small section of size corresponding to said small bore, said piston being slidable from a first position where said small section is substantially withdrawn from said small bore to provide a uid connection between said intake and outlet ports, to a second position where said small section is substantially wholly within said small bore, said piston having an annular groove in said small section and an annular groove in said large section positioned to remain on the side of said intake port remote from'said outlet port as said piston moves from said rst to said second position; and O-rings in each of said annular grooves in said piston, the O-ring on said small section being capable of making a sealing fit with the wall of said small bore when said piston is in said second position, thereby interrupting the fluid connection between said intake and outlet ports through said chamber, and the O-ring on said larger section making a sealing fit with the wall of saidlarge bore when said piston is in either said first or second position to prevent fluid passage from said intake port to the outer end of said large bore.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,444,984 Simmon Feb. 13, 1923 1,978,669 Carroll Oct. 30, 1934 1,987,435 Engel Jan. 8, 1935 2,057,707 Carroll Oct. 20, 1936 2,083,654 Kochmann June 15, 1937 2,252,482 Gates Aug. 12, 1941 2,289,318 Pratt July 7, 1942 2,394,343 Vorech Feb. 5, 1946 FOREIGN PATENTS Number Country Date 548,727 Great Britain Oct. 22, 1942 568,343 Germany Jan. 18, 1933 

